About ten years ago, a new category of game balls came into existence, namely, the safety game ball and particularly the safety baseball and the safety softball. These game balls are formed with polyurethane foam cores that are covered with a cloth cover having stitched seams. The primary feature of these balls is that they have a play value, performance, which approximates in many respects the performance of standard or regulation balls, but they produce an impact pressure when they hit players which is far less than the much harder regulation balls. U.S. Pat. Nos. 4,462,589 and 4,772,019 describe in detail these safety baseballs.
Safety baseballs are now being used by twenty-two of the twenty-six major league baseball teams as training tools. Similarly, many colleges, high schools and Little League teams use safety baseballs for training purposes. Safety baseballs also have been approved for use in T-Ball leagues as a game ball by Little League Baseball, Pony League Baseball, Dixie Youth Baseball and National Youth Sports Coaches Association. The present market for safety, and other resilient core, baseballs and softballs is estimated to be between 3 to 4 million units per year.
One of the drawbacks of the cloth-covered, safety game ball has been that the seams are not herringbone, flat-stitched seams. Cloth-covered safety game balls have been constructed with seams that are formed by cover edges which are pulled together and extend outwardly in a side-by-side relationship from the ball and are joined by loop-type stitching. Such raised, loop-stitched seams, however, have the aesthetic and psychological disadvantage of not having the same appearance as a regulation baseball or softball. Thus, for the "traditionalist" the non-regulation appearance of the ball outweighs the safety benefits. This has caused the safety balls to be used primarily in practice or non-competitive situations at higher levels of play, although the balls are used competitively in T-ball leagues, as indicated above.
Regulation baseballs and softballs have relatively flat seams in which the stitching is laid out in a herringbone pattern. The seam can be felt to be slightly raised relative to the remainder of the ball, but as compared to a safety baseball with its looped-stitched and outwardly-protruding seams, the regulation balls have flat or co-spherical seams with respect to the body of the balls.
The primary reason for the safety baseball protruding seam construction is that it is necessary in terms of safety to have an elastically-resilient core capable of substantial deformation. This elastic deformation of the core greatly reduces the impact pressure in the event that the ball hits a player. Moreover, the use of a cloth cover, as opposed to a regulation leather cover or a vinyl cover, further ensures low impact pressures by not materially contributing to the ball's hardness.
When a safety baseball is stitched with a conventional herringbone seam, however, the substantial deformation of the core causes the stitching to rip the cloth cover at the seams during the high energy impact with a bat. Thus, safety baseballs with flat, herringbone-stitched, seams have been found to have very poor durability.
Nevertheless, the pressure to eliminate the protruding loop-stitched seams of the safety baseball has remained. One solution has been to substitute a vinyl cover for the cloth cover. When a vinyl cover is used on a safety baseball core, the result is a game ball having lower impact pressure than a regulation ball, but such vinyl covered balls still have an impact pressure which is at least twice as high as a clothcovered ball. Thus, a substantial safety sacrifice is made when using a vinyl cover to obtain the appearance of herringbone stitching and flat seams. Nevertheless, in the safety baseball category, the current largest growth product is the vinyl covered ball, simply because it looks more like a regulation baseball.
There also have been leather-covered resilient, urethane foam core baseballs with flat-stitched, herringbone seams, but these balls have an even higher impact pressure which takes them out of the safety category.
Various other attempts have been made to provide a cloth-covered safety game ball with flat, herringbone-stitched seams. The edges of the cloth cover pieces have been seared or melted to form a ridge along the edges to try to prevent tearing at the seams during play. The result has been that the cloth covers continued to tear and the hard ridges along the seam were a safety concern. Additionally, a vinyl gasket has been adhered to the outer edge of a cloth cover and herringbone stitching used. The result was that seam tearing was reduced, but the nylon cloth cover and vinyl strip tended to delaminate, and the vinyl material formed a hard ridge along the seam that created a new safety hazard.
Accordingly, notwithstanding the widely recognized benefits of the safety game ball there has remained the constant appearance disadvantage of the protruding, loop-stitched seam. Essentially, this problem has relegated the safety game ball primarily to practice and training situations at higher skill levels and Tball in younger leagues and has produced a compromise game ball having a vinyl cover and resultant impact pressure that is undesirably high.